Doodling on the phone, Jean Dubuffet hit upon a form that was to occupy him for the next 12 years. The original sketches are on display in this overdue show, liquid shapes with red and blue hatching. He has trimmed the edges and stuck them down on black paper, surrounded them with jargon text of his own devising, and given birth to a series of works called L’Hourloupe.

Blown up onto sizeable canvases, in the central part of this show, his work in this style is liberating. Thick black lines encase cells of primary colour. The copious whiteness gives these works, between 50 and 40 years old, a freshness and a vitality that could perhaps only come from a doodle. Sadly, in the mobile era, such practice may be a dying art.

We have also lost the habit of locking up the insane, and Dubuffet would no doubt be pleased about this. The French painter took inspiration from the art of marginalised people.

He encouraged them, he collected them, and he gave their practice a genre: art brut. His collection travelled to the USA and came back to Paris in time for the L’Hourloupe series. It is perhaps the origin for the breath of freedom flowing through these works.

Site Habité d’objects is a case in point. Cells interlock as in a puzzle. The composition is emboldened by a tricolour palette. And as the title suggests, the work is a still life.

Dubuffet loved distortion, but he was no great fan of abstraction. Perhaps because that tendency smacked too much of the world of art and the training which he must have wanted to unlearn.

A roomful of these pieces all painted between 1964 and 1967 still has the power to excite. It was a new aesthetic, with the immediacy of a comic book, yet steeped in the mystery of a pure act of creation.

But that is also surely the mystery of the asylum as well. Dubuffet’s major series is a reminder of the Salvador Dalí quotation: “The only difference between me and a madman is that I’m not mad.”

L’Hourloupe has been well contextualised here at Pallant with a selection of his earlier works also present. We have Texturologie IX painted with sand and scraped over with a fork. We also have a suite of claustrophobic street scenes from Paris: Vire Volte, Paris Plaisir and Affluence. Debuffet’s energy and humour are already in evidence. Hats balance on heads and wide eyes sit above rictus grins.

1966 was the last time a public space reviewed this energetic and somewhat enigmatic painter. That year saw shows at Tate and the ICA. The Pallant show has therefore been long in coming and, were it not for the focus on one series, might have been too little, too late.

As things stand, any renewed interest in Dubuffet is to be welcomed; a full scale survey in a bigger space is surely not a crazy idea.